Production of vitamin d



Patented Feb. 7, 1933 'wngnm Arman:

UNITED STATES PATENT- oFric or ramnarcnsrnnn, Ann wanna runen, or

LUnwr-on-rnn-anmn omen, sssrenozas T0 wm'rnnor cnmcar. 001mm, me. or mzwroan, 1w. Y., a conromvrron or NEW YORK PRODUGIIQN O]? VITAMIN D I0Drawing. Application fled August 16, 1828, Serial 80. 800,156, and inGermany August 26, 1887.

The methods hitherto known and described for the preparation of theantithe intensity being as high as possible in order to accelerate thephotochemical transforination. The formation of the vitamin D has beencontrolled, qualitatively, by means of the observation of the changes inthe absorption spectrum of the solutions,

.and also by the specific physiological action attendant on itsformation. For the quanti- .tative determination, use .has been made ofthe chemical method of digitonine precipitation to record the diminutionof the er osterol. Y

e have now found by exact investigations of the absorption spectracarried out by means of special sources 0 ultra-violet light, forexample, a hydrogen lamp for, high voltage giving a continuousultra-violet spectrum, that it is possible also to directly ascertainquantitatively the amount of vitamin D formed, thus enabling theprogress of the photochemical reaction to be studied more exhaustively.Observations based on this method have led to a new process, by means ofwhich products with a maximum content of vitamin D can beobtained whileavoiding losses the source of which had hitherto not been discovered.The essence of the process resides in the fact that the I exposure ofergosterol, and especiall of its solutions, to the action of ultra vioet rays is reduced in intensity or alto ther suspended before all theergosterol h formed, so that the time at which maximum absorption in therange of the spectrum lying between A=3Q0 p and A=230a a 5 die forvitamin D occurs, is not, or is not su tantially exceeded.

It has been found that during the exposure of ergosterol dissolved, forexample, in alcohol, pentane, heptane, or: other solvents, toultra-violet rays the vitamin D appearssolel as an intermediate product,and that it, w en'the irradiation is continued,

e as been transunder oes transformation into a final prodnot w lClldifi'ers fundamentally from vitamin D in res ct of the absorptionspectrum, the said pro not also difiering from vitamin D in itsphysiological action. The formation of this final product maybe easilyde-.

tected by reason of the fact that on continuing the exposure of thesolutions to ultraviolet rays the characterisic absorption range forvitamin D revealed by a maximum extinction between A=300a p and A=230begins to grow brighter, and disappears entirely in the case of sampleswhich have been sub ected to a very considerable exposure to the actionof the said rays. 7

The fact thus disclosed, that vitamin D is a well defined intermediateproduct, and not a final roduct, of the photochemical treatment 0)?ergosterol may be further demonstrated inthe following manner. It hasbeen found impossible to reproduce a series of solutions obtained by theexposure of solutions of ergosterol to ultra-violet rays forprogressively longer periods of time and characterized by the nature oftheir absorption spectra, by merely mixing the initial solution of erterol in successively graduated proportions On the contrary, in order toreproduce the initial or final course of the said series, it isnecessary to mix with the initial or final product, in graduatedproportions, a solution whichhas been obtained by moderate irradiationand which contains a maxi.- mum content of vitamin D. By means ofstandard com arative mixtures prepared in this manner, it is possible toobtain quantitative determinations of the content of crgos terol,vitamin D and the final product present in irradiated samples. Also bymeans of this with the solution of the final product resulting fromintensive exposure to the action of the rays.

method, it can be easily ascertained that the photochemicaltransformation ergosterol vitamin D-final productproceeds in such a waythat, at that stage of the reaction at which maximum quantities ofvitamin D have been formed, they are still accompanied by considerableamounts, corresponding to the intensity of distribution of the sourceofradiant energy employed of ergosterol, and that,

on the other hand, when the ergosterol is completely exhausted, aconsiderable portion of the vitamin D has already been transformed intothe final product. Consequently a method like the one hithertocustomary, whichis based on the determination of the amount ofergosterol which has disappeared, must lead to an over-exposure whichconsiderabl impairs the yield of vitamin. This draw ack, however, iscompletely obviated by the present process.

The said process may be carried out in various ways. For example, theirradiation can be regulated and restricted by supervising the progressof the reaction by spectral analysis in an apparatus which is integrallyconnected with'the irradiation apparatus and which is traversed by thereaction liquid. Spectrographical or photoelectrical methods may be madeuse of and an automatic control can be provided by coupling theregistration apparatus with the source of irradiation, so that when thedesired optical condition is registered, the said source of irradiationis automatically out OK.

The adjustment of the irradiation in order to obtain a maximumproduction of vitamin D can also be efl'ected with an irradiation deviceof known capacity, in which the degree of ifiadiation necessary for amaximum output of vitamin D is kept within limits by continuouslypassing the solution under treatment before the source of light at sucha velocity that, by the time of issuingfrom the irradiation chamber, thedesired optical condition will have been attained.

, Finally, it has been found that, by a suitable selection of theworking conditions of the source of radiation or by the interposition ofsuitable light filters, which absorb the rays of a wave length which isshorter than A=290 for instance filters of a glass known under'thetrade-mark uviol glass, the radiation which produces the formation ofthe final product can be cut out, to a certain extent, from theradiation which is effective for the transformation of the ergosterolinto vitamin D, so that the undesired photochemical secondary reactioncan, to some extent, be suppressed.

The following examples "wlll further illustrate the nature of the saidinvention which however is not limited'thereto.

Example 1 i A. solution of ergosterol, for example, 5 grams ofergosterol in 5 litres of alcohol, is irradiated with ultra-violetlight. Samples of a few cubic centimetres each are taken at equalintervals, say every ten minutes and graph. The successive samples. showin creasing absorption between ,\=300 a and A=230u a. The attainment ofthe maximum absorption, within this range, for the total quantityirradiated, is ascertained by continuing to irradiate a sample which isalready strongely absorbent, until incipient brightening occurs, andthen comparing it with the samples previously taken. When the maximumabsorption is attained, the irradiation is suspended. The absorptionspectrum will then reveal, in conformity with a check digitonineprecipitation, the presence of l per cent of still unaltered ergosterol.

E mample 2 In order to enable a more reliable check to be obtained, theregular sampling of the irradiated solution is replaced by a testingapparatus integrally connected to the irradiation apparatus, andconsisting of a test glass, with feedandjdischarge tube, which iscontinuously traversed by the irradiated solution. In this deathsmeasurement of the absorp tion is preferably effected continuously, forexample by means-of a photoelectrical cell which is sensitive only inthe region between ,\=300;r a and A=230a a, and which emits a minimum ofphotoelectric current at the moment the vitamin :01am attains a maximum.By means of an amplifying device, the photoelectric cell can also bearranged to shut oil the source of irradiation automatically on themaximum content of vitamin being attained.

Example 3 The irradiation of the ergosterol is efi'ected in a continuousmanner, an irradiation vessel, in the form of a cylinder 30 centimetreslon and 5 centimetres internal diameter, Wit terminal intake and outlettubes, being employed for this purpose. In this case, the testing{apparatus is integrally connected to the outlet tube. By regulating therate of flow, by means of a pump or high level stora e vessel, it caneasily be arranged that the liquid issues from the irradiation vessel inthe desired condition. In the case of a uartzmercury lamp the correctvelocity lies between 1 and 2 cubic centimetres per second. If thetransformation of ergosterol is below the desired degree, the rate offlow is reduced, while if the maximum of the vitamin'content -is passed,the rate of flow is increased. The

apparatus for the further treatment of the vitamin solutions is attacheddirectly to the irradiation device. A I

What we claim is: 1. Theimprovement in the production of vitamin D byexposing a solution of ergosterol to-the action of ultra-violet rayswhich comprises passing a solution of ergosterol by a source ofultra-violet rays, sup'ervisin the progress of reaction by spectralanalysis of part ofthe reaction mixture and interrupting the exposurebefore all of the ergosterol is transformed and before the maximumabsorption in the range of the s ectrum between A=300 a and X=230p p.speclfic to vitamin D is substantially exceeded. a 2. In the productionof vitamin D by exposing ergosterol to the action of ultra-violet rays,the steps comprising irradiating the crosterol, supervising the progressof reaction posure before the maximum absorption in the range of thespectrum between A=Q p and /\=230; 1. is substantially exceeded.

3. In the-production of vitamin D by exposing ergosterol to the actionof ultra-violet rays, the steps comprising irradiating the ergosterol inthe form of a solution, supervising the progress I of reaction byspectral analysis and interrupting the exposure before the maximumabsorptionin the range of the s ectrum between )t=300p a and A=230 p issubstantially exceeded. I

4.- In the production'of vitamin D by exposing ergosterol to the actionof ultra-violet rays, thesteps comprising irradiating the crgosterol,supervising the regress of 'reaction by spectral anal sis and interru'ting the exposure at about mum absorption in the range of the spectrumbetween A=300 p. and A=230 p has been reached.

In testimony whereof we have hereunto set our hands. I WILHELM'ZIMMERMANN.

- WALTER F RANKENBUBGER.

y spectral analysis and interrupting the'ex e time when t e ,maxi- 4

